Registers TrailerIntroProvider as IIntroProvider. Queries fake-movie
items in the output folder and returns their local trailer extras
(LocalTrailers) as IntroInfo — mirroring jellyfin-plugin-cinemamode's
proven pattern so Wholphin plays the actual trailer, not the 3-second
black placeholder.
Recursion guard: items whose path starts with the output folder are
excluded from intro injection, so Wholphin's getIntros call on the
intro item itself returns empty. Server-scoped query bypasses library
visibility restrictions so hidden trailer libraries still work.
Adds TrailersPerMovie config option (default 1, 0 = disabled).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
